#005188

CSS

:root {
  --dark-denim: #005188;
  --dark-denim-rgb: 0 81 136;
  --dark-denim-oklch: oklch(0.424 0.113 247.6);
}

.element {
  color: var(--dark-denim);
  background-color: hsl(204 100% 27%);
  border-color: oklch(0.424 0.113 247.6);
}

Tailwind CSS v4

@theme {
  --color-dark-denim: #005188;
  --color-dark-denim-50: #ddf9ff;
  --color-dark-denim-100: #ccecff;
  --color-dark-denim-200: #b0d9ff;
  --color-dark-denim-300: #8abcef;
  --color-dark-denim-400: #65a4de;
  --color-dark-denim-500: #408bcd;
  --color-dark-denim-600: #3776ad;
  --color-dark-denim-700: #2c5e8b;
  --color-dark-denim-800: #1c4667;
  --color-dark-denim-900: #123048;
  --color-dark-denim-950: #041c2f;
}

SCSS

$dark-denim: #005188;
$dark-denim-rgb: 0, 81, 136;
$dark-denim-light: mix(#fff, $dark-denim, 20%);
$dark-denim-dark: mix(#000, $dark-denim, 20%);

.element {
  color: $dark-denim;
  box-shadow: 0 0 0 2px rgba($dark-denim, 0.35);
}